Omeprazole

Information about Omeprazole

Omeprazole and esomeprazole are proton pump inhibitors (PPIs) and potent inhibitor of gastric acidity which are widely used in the therapy of gastroesophageal reflux and peptic ulcer disease. 

Liver safety of Omeprazole

Omeprazole and esomeprazole therapy are both associated with a low rate of transient and asymptomatic serum aminotransferase elevations and are rare causes of clinically apparent liver injury.

Mechanism of action of Omeprazole

Omeprazole (oh mep' ra zole), like other PPIs, inhibits gastric acid production by binding to and inactivating the H+/K+-ATPase of gastric parietal cells, causing inhibition of the proton pump that transports H+ into the gastric lumen, the common final step in gastric acid production.  Omeprazole is a prodrug and is converted to the active form (sulfenic acid) in the acidic secretory canaliculi of parietal cells.  Because the inhibition is irreversible, acid secretion is suppressed for 24 to 48 hours, until new proton pump molecules have been synthesized and transported to the cell membrane.  Omeprazole was the first PPI approved for use in the United States (1989), initially only for the indication of severe peptic ulcer disease and Zollinger-Ellison syndrome.  Subsequently, the indications for its use have broadened to routine peptic ulcer disease, gastroesophageal reflux disease and prevention of stress ulcers. 

Omeprazole and esomeprazole are two of the most widely used medications in clinical practice with more than 20 million prescriptions filled yearly in the United States alone.  Omeprazole is available in multiple forms including 10, 20 and 40 mg standard and delayed release capsules and powder for oral suspension in generic forms and under the brand name of Prilosec.  The typical dose of omeprazole is 20 mg once daily with twice daily doses for more severe cases of gastrointestinal reflux and peptic ulcer disease, and doses of up to 120 mg daily for Zollinger-Ellison syndrome.  A 10 to 14 day course of omeprazole in combination with antibiotics is effective and recommended for the eradication of H. Pylori infection.  

Dosage and administration for Omeprazole

Both omeprazole and esomeprazole are very well tolerated and both are now available without prescription in multiple over-the-counter forms. 

Side effects of Omeprazole

Side effects of omeprazole and esomeprazole are uncommon and usually mild; they include diarrhea, nausea, vomiting, abdominal discomfort, flatulence, skin rash, headaches and dizziness. Severe side effects are rare but can include hypersensitivity reactions.  Long-term use of rabeprazole may be associated with bone fractures, acute interstitial nephritis, lupus erythematosus, vitamin B12 deficiency and hypomagnesemia.

The antiulcer agents in clinical use

Proton Pump Inhibitors

• Dexlansoprazole
• Esomeprazole
• Lansoprazole
• Omeprazole
• Pantoprazole
• Rabeprazole

Selective Histamine Type 2 Receptor Antagonists or H2 Blockers

• Cimetidine
• Famotidine
• Nizatidine
• Ranitidine

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